[cifs-protocol] Please clarify LSA and OsVersion behaviour in MS-NRPC (SRX090727600015)

[Andrew Bartlett]

On Mon, 2009-08-24 at 07:35 -0700, Bill Wesse wrote:
> Andrew - I think I might have missed a previous email of yours. If so, I offer my apologies.
> 
> The actual Windows behavior is - as Matthias noted previously - that
> NetrLogonGetDomainInfo bypasses the servicePrincipalName constraints
> (which are documented in [MS-ADTS] 3.1.1.5.3.1.1.4).

OK, When will this security bug be addressed?  I thought I saw a
difference in this behaviour for Windows 2008 - honestly I was expecting
'Windows 2008 fixed this' as your reply. 

> We are currently working on which document this should be addressed in
> ([MS-ADTS] or [MS-NRPC]). I expect that [MS-NRPC] is not the correct
> place, since SPN validation is carried out by Active Directory,
> outside the scope of the NetLogon protocol. I do not yet have any
> information concerning whether or not any product bugs will be filed,
> but I have alerted the appropriate folks here at Microsoft. That may
> impact any forthcoming Windows Behavior notes.

OK.  I would appreciate an update on what the expected long-term
behaviour of Microsoft products will be, so we know what we must
emulate.  (Oh the joys of bug-for-bug compatibility)

> [MS-ADTS]:
> Active Directory Technical Specification
> 3.1.1.5.3.1.1.4   	servicePrincipalName
> 	The object has class computer (or a subclass of computer).
> 	In AD DS, the servicePrincipalName value satisfies the following constraints:
> o	The SPN is a syntactically correct two-part SPN (see section 5.1.1.4, "Mutual Authentication").
> o	The instance name matches one of the following: the full DNS name of the machine, the sAMAccountName of the machine (without the terminating "$"), one of the msDS-AdditionalDnsHostName, or one of the msDS-AdditionalSamAccountName (without the terminating "$").
> 
> The guidance I provided earlier addresses these constraints; I regret omitting the reference to [MS-ADTS] 3.1.1.5.3.1.1.4 servicePrincipalName.
> 
> > Before updating the servicePrincipalName attribute ("HOST/dNSHostName") for the account under the established secure channel, the following checks would be prudent:
> >
> >    Reference:
> >    [MS-ADA3]: Active Directory Schema Attributes N-Z
> >    2.252 Attribute servicePrincipalName
> >
> > 1. NETLOGON_WORKSTATION_INFO.DnsHostName must match the client (machine) account sAMAccountName attribute (minus the trailing '$' character) for the account under the established secure channel.
> >
> >    Reference:
> >    [MS-ADA3]: Active Directory Schema Attributes N-Z
> >    2.221 Attribute sAMAccountName
> >
> > 2. NETLOGON_WORKSTATION_INFO.DnsHostName must match the client (machine) account dNSHostName attribute for the account under the established secure channel.
> >
> >    Reference:
> >    [MS-ADA1]: Active Directory Schema Attributes A-L
> >    2.185 Attribute dNSHostName
> >
> > 3. NETLOGON_WORKSTATION_INFO.DnsHostName must have an allowed DNS suffix (e.g., the domain DNS name).
> >
> >    Reference:
> >    [MS-ADA2]: Active Directory Schema Attributes M
> >    2.181 Attribute msDS-AllowedDNSSuffixes

Thanks for the detail.  I look forward to being able to use it some
day :-)

Andrew Bartlett

-- 
Andrew Bartlett
http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Cisco Inc.
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